The Aporphine-Pavine Dimers

Among the isoquinoline alkaloids, the aporphine-benzylisoquinolines had been considered a terminal stage of anabolic development in the biogenetic tree. The discovery of pennsylpavine and pennsylpavoline, two examples of a new group of dimeric alkaloids, the aporphine-pavines, has extended the biogenetic locus, since they are probably derived from aporphine-benzylisoquino-line dimers. 

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A continuing investigation of the alkaloids of Thalictrum polygamum Muhl. has resulted in the isolation of members of an interesting and novel isoquinoline group, the aporphine-pavine dimers. Pennsylpavine (59) and pennsylpavoline (60) are weakly basic phenolic alkaloids which are accompanied in the plant by the aporphine-benzylisoquinolines pennsylvanine (46) and pennsylvanamine (47). It therefore seems likely that (46) and (47) are biogenetic precursors for (59) and (60), respectively. ... 

Comparison of the structures of pennsylvanine and pennsylvanamine, two dimers of the ( + )-thalicarpine series which co-occur with pennsylpavine and pennsylpavoline, furnishes prima facia evidence that aporphine-benzyliso-quinolines could act as biogenetic precursors to the aporphine-pavine dimers. 

The second dimeric base, (—)-pennsylpavoline (179), was shown to correspond to C-l-demethylpennsylpavine. Specifically, its NMR spectrum was devoid of the 8 3.71 singlet which represents the C-1 methoxyl absorption in (—)-pennsylpavine (178). Evaluation of CD spectra of these novel dimers and comparison with those of the aporphine (+)-A -methyllaurotetanine and the pavine (—)-platycerine led to the assignment of the absolute configurations as depicted in expressions 178 and 179. These dimers are probably derived biosynthetically from the aporphine-benzylisoquinoline dimers, (-)-pennsylvanine and (-)-pennsylvanamine, which were found in the same plant (7,173). 

Fourteen alkaloids were isolated from extracts of the whole plant of ThaUctrum fauriei Hayata, among which were seven alkaloids of novel structure including three aporphines (3-0-demethyloconovine, faurine, and O-methylfaurine), three aporphine-benzylisoquinoline dimers (fauridine, faurithaline, and 3-methoxyfaurithaline), and one aporphine-pavine dimer (fauripavine). Alkaloids of previously established structure that were isolated and identified included five aporphines (corydine, isocorydine, isooconovine, oconovine, and thalisopynine), and two morphinans (ocobotrine and pallidine). 

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